Balancing means for oscillating cylinder machines



Aug. 24 19.26.

' A. R. STEVENSON. JR BALANCING MEANS FOR LOSOILLATING CYLINDER maxim-2sFiled March 26, 1926 lll W o. w w n 9 mr E. K 7

UNITED STATES,

PATENT OFFICE.

ALEXANDER n. s'rnvnnson, an, or sonnnnoran new YORK, Assrenon T GEN- 9Emu; ELECTRIC COMPANY, A CORPORATION on new YORK.

BALANCING MEANS FOR GSCILLATING CYLINDER MACHINES.

. Application filed March 26, 1926. SerialN'o. 97,794.

My invention relates to machines which comprise a cylinder, a pistontherein and a shaft, and particularly to such machines in which thecylinder oscillates and the piston engages an eccentric member rotatablewith the shaft. It is well known that when such a machine is operated.at relatively high speed the rapidly moving parts may produceconsiderable vibration. A certain amount of this vibration has beenavoided in the past by applying a counterweight to the shaft topartially balance the piston and its connection with the shaft. Apartial balance only jwasproduced for the reason that it was known thatif the counterweight were made sufiicientlyheavy to effect a completebalance of the parts in the general direction of the cylinderto reducevibration in that direction it would very much overbalance the parts inthe transverse directionand would produce excessive vibration in thelatter direction. Hence it has been customary to make a compromise inthe balance in these two directions bymaking the counterweightapproximately only half of what itshould be to balance the parts in thedirection of the cylinder although greater than it should be to balancethe direction. I

It is an object of my invention to provide an improved machine of thischaracter in which the moving parts are substantially balanced both inthe general direction of the cylinder and in the direction transversethereto, whereby'the machine may be operated at a relatively high speedwithout producingan. objectionable amount of vibration.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing, and its scope will bepointed'out in the appended claims.

Referring to the drawing, Fig. 1 is a perspective view of one embodimentof my invention; Fig. 2 is a top plan view of the same; and Fig. 3 is alongitudinal section thereof.

While my invention is equally applicable to either an engine or a pump,I have chosen to illustrate it as applied to the compressor of arefrigerating machine such as that disclosed in the copendingapplication or parts in the transverse the general direction-of thecylinders, that eccentric 2 thereon which is engaged by the eccentricstrap portions 3 and 4 respectively of the two pistons 5 and 6. Theframe 7 which provides a bearing for the shaft 1' has two flat bearingfaces 8 and 9 on which the two oscillating cylinders 10 and 11respectively rest. Each cylinder has a trunnion 12 on its lower'sidejournalled in the frame 7. Each cylinder is shown held down on its seatby means of a spring 13 which at its upper end bears against a part ofthe frame and at its lower end carries a plate 141- which bears againsta ball 15 resting in a depression in the top of the cylinder. Eachcylinder is also shown provided with an intake port 16 which cooperateswith a suitable port in the frame 7 and with an exhaust valve 17 whichis covered by a muffler 18.

The counterweight, which I have shown as comprising the two weights 20and 21, is applied to the shaft on the side opposite to the center ofthe eccentric 21. I construct this counterweight such that itsubstantiallybalances the eccentric and the two pistons in is, when theshaft' is at right angles to that shown in. Fig.2, the moving parts aresubstanti ally in static balance in the direction of the cylinders. tothe upperyface of the eccentric 2 by means of the plates 22 and theweight 21 is shown secured to the shaft by means of cylinders it will.be far too heavy to balance the parts in the transverse direction sincewhen the parts are in the position shown in Fig. 2 the pistons arepartially supported by the cylinders. The cylinders lVeight2O is shownsecured moreover have their centers of gravity approximately coincidentwith their pivotal centers. I

In accordance with my invention, after thus balancing the parts in thedirection of the cylinders I produce acondition of balance also in thetransverse direction by adding Weight to the cylinders between theirpivoted centers and the shaft. For this purpose I have shown eachcylinder provided with a pair of diverging arms or counterweights and 26which have the effect of shifting the center of gravity of eachcylinder, otherwise approximately coincident with its pivotalcenter,-=to anew position between its pivotal center and its open end.The arms and 26, it will be noted, move in the opposite direction tothat of the counterweight when the parts pass the position shown in Fig.2 and a proportionate amount of their weight is added to that of theeccentric which must bebalanced by the counterweight. By suitablyproportioning these arms a condition of substantial static balance isobtained relative tothe transverse direction or diretion atright anglesto the cylinders. In-

asmuch as the cylinders have only oscillating movement the presence ofthe arms 25 and 26 does not appreciably affect the balance of the partsin the direction of the length of the cylinders. It will therefore beseen that in my. machine the moving parts are substantially balancedboth in the direction. of the cylinders and in the transverse directionand for this reason the machine may be operated at a relatively highspeed without an objectionable amount of vibration resulting therefrom.

What I claim as new and desire to. secure by Letters Patent of theUnited States, is 1. In combination, a rotatable shaft, an oscillatablecylinder, a piston therein, a. drive connection between the shaft andthe piston, means associated with the shaft for producin g substantialbalance in thelongitudinal direction of the cylinder and meansassociated with the cylinder and cooperating with said means forproducing substantial balance 3. A compressor comprising a drive shaft,

an oscillatable cylinder, a piston therein having ane'ccentricconnection with the shaft,

counterweight means rotatable with the shaft for producing substantialbalance in the longitudinal direction of the. cylinder, andcounterweight means carried by the cylinder and-cooperating with saidfirst means for producing substantial balance in the direction at rightangles to the longi,

tudinal direction of the cylinder;

4:. A compressor comprising a drive shaft having an eccent-ricthereon, apair of pivot'-.

ally mounted cylinders arranged on opposite sides thereof, a piston ineach cylinder having an eccentric strap engaging said eccentric, acounterweightcarried by the shaft for balancing the eccentric and thepistons in the direction of the cylinders, and counterweights carried bythe cylinders between their pivotal centers and .the shaft. 5. Acompressor comprising a drive shaft having an eccentric thereon, a pairof pivot ally mounted cylinders arranged on opposite sides thereof, apiston in each cylinder hav ing an-eccentric strap engaging'theeccentric, and a counterweight on the shaft arranged on the sidethereof opposite to .the eccentric, said cylinders each having a pair ofextensions forming weights projecting toward the shaft and arranged inopposite sides of the piston. j I

In witness whereof, I have hereto set my hand this'2 5th day of March,1926.

ALEXANDER R. STEVENSON, JR.

